The present invention relates to a control apparatus for a three-dimensional laser beam machine having a head structure in which the processing point is not moved when the rotation axis and the attitude axis are rotated, the control apparatus having a function of, based on a nozzle direction vector, displaying an angle of a nozzle in a vertical direction consisting of the Z-axis of an orthogonal coordinate system, and an angle in a horizontal direction when the nozzle direction vector is projected to the XY-plane.
Hereinafter, the configuration of a three-dimensional laser beam machine that machines a planar or three-dimensional workpiece shape, and that has a structure of a head in which the processing point is not moved when the rotation axis and the attitude axis are rotated (hereinafter, such a head is referred to as unidirectional head) will be described with reference to FIGS. 6, 7, and 8.
FIG. 6 is a perspective view showing the configurations of axes of a three-dimensional laser beam machine on which a unidirectional head is mounted, FIGS. 7A and 7B are enlarged views of a processing head of the three-dimensional laser beam machine on which a unidirectional head is mounted, and FIG. 8 is a block diagram showing the configuration of the three-dimensional laser beam machine.
In the figures, 109 denotes an attitude axis (hereinafter, referred to as U-axis) which is positioned at the drive end of an arm 111, 110 denotes a rotation shaft (hereinafter, referred to as W-axis) which is connected to the U-axis 109, and 108 denotes a Z-axis which is connected to the W-axis 110. These axes constitute the arm 111.
The processing head 3 has: the W-axis 110 which is placed at the tip end of a Z-axis bearing 115, and which can be rotated in a direction of an arrow +xcex1 or xe2x88x92xcex1 about the Z-axis by a rotary bearing 114; and the U-axis 109 which is attached to the tip end of the W-axis 110 by an attitude bearing 113, and which can be rotated in a direction of an arrow +xcex2 or xe2x88x92xcex2 about an axis that is inclined by 45 degrees with respect to the Z-axis. A processing nozzle 4 is attached to the tip end of the U-axis 109. Since the U-axis 109 is rotated about the axis which is inclined by 45 degrees with respect to the horizontal plane, the angle of the U-axis does not correspond in a one-to-one relationship to the vertical angle at which the processing nozzle 4 is directed.
The reference numeral 113 denotes the attitude bearing which rotates the U-axis 109 by a servo motor SM5 in the direction of the arrow +xcex2 or xe2x88x92xcex2, and 114 denotes the rotary bearing which rotates the W-axis 110 by a servo motor SM4 in the direction of the arrow +xcex1 or xe2x88x92xcex1.
The reference numeral 115 denotes the Z-axis bearing which moves the processing head 3 by a servo motor SM3 in the direction of an arrow Z, 116 denotes a Y-axis bearing which moves the processing head 3 by a servo motor SM2 in the direction of an arrow Y, and 117 denotes an X-axis bearing which moves a processing table 2 by a servo motor SM1 in the direction of an arrow X. The servo motors SM1 to SM5 are driven by a driving signal from an NC controller 8. The reference letter P denotes a processing point the position of which is not moved even when the W-axis 110 and the U-axis 109 are rotated.
The reference numeral 105 denotes a laser oscillator which generates a laser beam, and 103 denotes an operation section through which the NC controller is operated.
When laser beam processing is to be conducted by using the thus configured laser beam machine, it is requested in laser beam processing which machines a planar or three-dimensional workpiece shape that the direction and posture of the processing nozzle 4 are always perpendicular to the processing plane in order to maintain the optical axis of the laser beam irradiating the processing plane to be normal to the processing plane. Before conducting processing, therefore, the operator makes the processing point P coincident with a point (hereinafter, referred to as teaching point) on a processing line K of a processing workpiece 9, and in advance of actual processing conducts a teaching work in which a teaching point satisfying the requirement is input as a teaching data into a program.
During laser beam processing, in accordance with the teaching data, the spot of the laser beam is controlled so as to advance along the processing line K while maintaining the distance of the processing head 3 with respect to the processing workpiece 9 to be constant.
FIG. 9 is a view showing angles of horizontal and vertical components of a unit vector (hereinafter, referred to as nozzle direction vector) in a direction indicated by the processing nozzle 4 from the angles of the W-axis 110 and the U-axis 109, in a coordinate system (hereinafter, referred to as orthogonal coordinate system) in which the XY plane is defined as a horizontal plane and X-, Y-, and Z-axes are outer products of the other axes or relationships of Yxc3x97Z, Zxc3x97X, and Xxc3x97Y are established. The reference numeral 70 denotes a teaching point in an inclined portion of a workpiece, and 71 denotes a line segment formed by the origin O and the teaching point 70, i.e., the nozzle direction vector.
The reference numeral 72 denotes a point which is obtained by projecting the teaching point 70 onto the XY-plane, 73 denotes a line segment which is obtained by projecting the line segment 71 onto the XY-plane, i.e., a line segment which is formed by the origin O and the point 72, 74 denotes the X component dx at the processing point 70, 75 denotes the Y component dy at the processing point 70, 76 denotes the Z component dz at the processing point 70, xcex8 denotes an angle xcex8 of the vertical component formed by the line segment 71 and the Z-axis, and xcfx86 denotes an angle xcfx86 of the horizontal component formed by the line segment 73 and the X-axis. In FIG. 9, because of the structure of the processing head 3, it is known that the nozzle direction vector d is given from the angle xcex1 of the W-axis 110 and the angle xcex2 of the U-axis 109 as:   d  =            (                                    dx                                                dy                                                dz                              )        =          (                                                                                                        1                    2                                    ·                  cos                                ⁢                                  xe2x80x83                                ⁢                α                            -                                                                    1                    2                                    ·                  cos                                ⁢                                  xe2x80x83                                ⁢                                  α                  ·                  cos                                ⁢                                  xe2x80x83                                ⁢                β                            +                                                                                          2                                        2                                    ·                  sin                                ⁢                                  xe2x80x83                                ⁢                                  α                  ·                  sin                                ⁢                                  xe2x80x83                                ⁢                β                                                                                                                                                                    -                                              1                        2                                                              ·                    sin                                    ⁢                                      xe2x80x83                                    ⁢                  α                                +                                                                            1                      2                                        ·                    sin                                    ⁢                                      xe2x80x83                                    ⁢                                      α                    ·                    cos                                    ⁢                                      xe2x80x83                                    ⁢                  β                                +                                                                                                    2                                            2                                        ·                    cos                                    ⁢                                      xe2x80x83                                    ⁢                                      α                    ·                    sin                                    ⁢                                      xe2x80x83                                    ⁢                  β                                            ⁢                                                                                                         1                2                            +                                                                    1                    2                                    ·                  cos                                ⁢                                  xe2x80x83                                ⁢                β                                                                                        xe2x80x83                                          )      
When a polar coordinate system is used, the relationships between the components dx, dy, and dz at the teaching point 70 in FIG. 9 and the angles of the horizontal component and the vertical component are obtained by the following expressions:
cos xcex8=dz 
tan xcfx86=dy/dx 
From the expressions, the angles in the horizontal and vertical directions are obtained.
xcex8=a cos(dz) 
xcfx86=a tan(dy/dx) 
As described above, the conversion expressions contain an inverse trigonometric function. In the case where only the angle xcex2 of the U-axis 109 is known, it is impossible to read the angle xcex8 of the vertical component by which the processing nozzle 4 is directed.
The above is similarly applicable to the relationship between the W-axis 110 and the angle xcfx86 of the horizontal component.
FIGS. 10A and 10B are views showing an attitude change of the processing head in a teaching process, and processing in which the incident angle of the laser beam is inclined, FIG. 10A shows an attitude change of the processing head in a teaching process and in an attitude change corner portion in a three-dimensional laser beam machine having a head structure in which the processing point is not moved when the W-axis and the U-axis are rotated, and FIG. 10B is a view showing processing (hereinafter, referred to as taper processing) in which the incident angle of the laser beam is inclined with respect to the surface of the workpiece.
In the figure, P1 denotes a teaching point which is on the processing line K of the processing workpiece 9 and on a horizontal plane, P2 denotes a teaching point which is on the processing line K of the processing workpiece 9 and on a 45-degree inclined plane, P3 denotes a teaching point which is on the processing line K of the processing workpiece 9 and on an uprighting plane, 3a and 4a denote a processing head and a processing nozzle which are downward directed at the teaching point P1, 3b and 4b denote a processing head and a processing nozzle which are directed to 45 degrees at the teaching point P2, and 3c and 4c denote a processing head and a processing nozzle which are horizontally directed at the teaching point P3.
When teaching is to be conducted, the operator reads the shape of a completed workpiece from a predetermined drawing for conducting laser beam processing. Based on the shape, the operator then scribes the processing line K on a workpiece for producing teaching data, and determines the nozzle angle at each of the teaching points on the processing line K. When a perpendicular state is to be then established at each of the teaching points P1, P2, and P3 on the processing workpiece 9, the nozzle angles are adjusted to 0xc2x0, 45xc2x0, and 90xc2x0 which are workpiece inclination angles determined from the drawing.
In FIG. 10B, A denotes a designated angle in the taper processing, and the nozzle angles are requested to be adjusted to this value.
The operator cannot calculate correct values of the W- and U-axes from the nozzle angles which are determined from the drawing. Therefore, it is difficult to attain numerical coincidence, and approximate values only can be estimated at the best.
FIG. 11 is a view showing a conventional coordinate display screen that displays coordinates of axes in a machine coordinate system in which a characteristic position defined by a machine is used as the origin. The screen is displayed during a teaching work.
In the screen, the position (hereinafter, referred to as tip end position) of the processing point P which is at the tip end of the processing nozzle 4 on the X-, Y-, and Z-axes is shown with respect to the machine origin peculiar to the machine, and the attitude of the processing nozzle 4 is indicated by means of the angles xcex1 and xcex2 of the W- and U-axes.
When the X-, Y-, Z-, W-, and U-axes are further moved, the values of the axes on the screen are updated on occasion in accordance with the movement.
Since a teaching data is produced by using the coordinates, the values of the W- and U-axes are necessary in processing to control the spot of the laser beam to advance along the processing line K by means of processing in the NC.
However, there are few situations where such values are handled as information to be indicated to the operator.
FIG. 12 shows a flowchart of a conventional teaching work in an inclined portion of a workpiece or taper processing.
As preparations for a teaching work in which a three-dimensional program is prepared by teaching of processing points, various items such as effectiveness of the use of a teaching box (hereinafter, abbreviated to T/B) 7 are set, and commands such as shutter opening of auxiliary function codes which are default settings in a processing program are set in step ST11.
While seeing the coordinates of the X-, Y-, and Z-axes on the coordinate display screen shown in FIG. 11, thereafter, the tip end position is moved in step ST12 to a teaching point by using a processing shaft feed key disposed on the T/B 7, or a handle and a joy stick.
At this time, if the angles of the processing nozzle 4 must be adjusted by teaching in an inclined portion of a workpiece or taper processing (step ST13), the W-axis 110 and the U-axis 109 are manually rotated in step ST14 in order to set the attitude of the processing nozzle 4.
In step ST15, step ST14 is repeated until it is affirmed as a result of checking of the nozzle angles by visual inspection that the perpendicular state is realized or the angles in the taper processing are attained.
After the setting of the tip end position and the attitude at the teaching point is ended in step ST15, teaching is conducted as teaching data in step ST16.
Subsequently to the above, while seeing the coordinate display shown in FIG. 11, the tip end position is similarly moved to the next teaching point by using the processing shaft feed key disposed on the T/B 7, or the handle and the joy stick, and teaching points of the processing program are produced by the teaching work.
In the case of a teaching work in which the angles of the processing nozzle 4 are not adjusted in step ST13, the works of steps ST14 and ST15 are omitted.
Finally, commands such as shutter closing and program end of auxiliary function codes are input in step ST18, and the preparation of the processing program is ended.
In a teaching work in a three-dimensional laser beam machine having the head structure of FIGS. 7A and 7B, conventionally, the method of the flowchart shown in FIG. 12 is established as a standard operation.
Because of visual checking, however, the accuracy of the adjustment of the nozzle angles in the perpendicular state and the taper processing is so poor that satisfactory processing is hardly realized. Moreover, the teaching work requires a long time period.
In the work of checking the position and attitude of each teaching point immediately before processing, when the angles of the W-axis 110 and the U-axis 109 are to be changed, it is necessary to readjust the attitude at the teaching point, and the attitude is corrected on the basis of the operations of steps ST13 to ST16 of the above-mentioned flowchart.
For the purpose of reference, the configuration of a three-dimensional laser beam machine having a structure of another kind of head type (hereinafter, referred to as offset type head) which is provided with a slim processing head, and which is suitable for processing of a deep drawing workpiece will be described with reference to FIGS. 13 and 14.
FIG. 13 is a perspective view showing the configurations of axes of a three-dimensional laser beam machine on which an offset type head is mounted, and FIGS. 14A and 14B are enlarged views of a processing head of the three-dimensional laser beam machine on which an offset type head is mounted. The components denoted by the same reference numerals as those of the three-dimensional laser beam machine on which the unidirectional head shown in FIGS. 7A and 7B is mounted are structured in a substantially same manner, and the portion of the arm 111 is differently configured.
Referring to the figures, the processing head 4 has: a rotation axis (hereinafter, referred to as C-axis) 122 which is placed at the tip end of the Z-axis member 115, and which can be rotated in a direction of an arrow +xcex1xe2x80x2 or xe2x88x92xcex1xe2x80x2 about the Z-axis by the rotary bearing 114; and an attitude axis (hereinafter, referred to as A-axis) 121 which is attached to the tip end of the C-axis 122 by the attitude bearing 113, and which can be rotated in a direction of an arrow +xcex2xe2x80x2 or xe2x88x92xcex1xe2x80x2 about an axis (the C-axis 122) that is perpendicular to the Z-axis. The processing nozzle 4 is attached to the tip end of the A-axis 121.
The angle of the A-axis 121 corresponds in a one-to-one relationship to the vertical angle of the processing nozzle 4, and that of the C-axis 122 corresponds in a one-to-one relationship to the horizontal angle of the processing nozzle 4.
Next, also with respect to the offset type head, relationships between the angles of the rotation axis and the attitude axis, and the angles of the horizontal component and the vertical component of the nozzle direction vector are shown.
In FIG. 14B, because of the structure of the processing head 3, it is known that the nozzle direction vector dxe2x80x2 is given from the angle xcex1xe2x80x2 of the C-axis 122 and the angle xcex2xe2x80x2 of the A-axis 121 as:       d    xe2x80x2    =            (                                    dx                                                dy                                                dz                              )        =          (                                                  sin              ⁢                              xe2x80x83                            ⁢                                                α                  xe2x80x2                                ·                sin                            ⁢                              xe2x80x83                            ⁢                              β                xe2x80x2                                                                                        cos              ⁢                              xe2x80x83                            ⁢                                                α                  xe2x80x2                                ·                sin                            ⁢                              xe2x80x83                            ⁢                              β                xe2x80x2                                                                                        cos              ⁢                              xe2x80x83                            ⁢                              β                xe2x80x2                                                        )      
When a polar coordinate system is used, the relationships between the components dx, dy, and dz at the teaching point 70 in FIG. 9 and the angles of the horizontal component and the vertical component are obtained by the following expressions:
cos xcex8=dz 
tan xcfx86=dy/dx 
From the expressions, the angles of the horizontal component and the vertical component are obtained.
xcex8=xcex2xe2x80x2
xcfx86=90xc2x0xe2x88x92xcex1xe2x80x2
Even when only the angle xcex2xe2x80x2 of the A-axis 121 is known, it is possible to read the angle xcex8 of the vertical component by which the processing nozzle 4 is directed.
The above is similarly applicable to the relationship between the C-axis 122 and the angle xcfx86 of the horizontal component.
FIG. 15 shows a flowchart of a teaching work in the three-dimensional laser beam machine having an offset type head.
Referring to the figure, operations of the steps up to step ST22 are identical with those of the steps up to step ST12 of the unidirectional head shown in FIG. 12. Thereafter, in the case where the angles of the processing nozzle 4 are required to be adjusted (step ST23), a tip end fixing mode in which tip end position is fixed and the C-axis 122 and the A-axis 121 are rotated to match the attitude is set in step ST24.
While seeing the display of the angles the C-axis 122 and the A-axis 121 on the coordinate display screen, the C-axis 122 and the A-axis 121 are rotated in step ST25 until a perpendicular state is attained in a known inclined portion of a workpiece such as shown in FIG. 14A, or the processing nozzle 4 is set to the angle for the taper processing.
After the setting of the tip end position and the attitude at the teaching point is ended, teaching is conducted as teaching data in step ST26.
Operations of subsequent steps ST27 and ST28 are identical with those of steps ST17 and ST18 of the unidirectional head shown in FIG. 12.
In the teaching work in the three-dimensional laser beam machine having the conventional head structure shown in FIG. 13, the shape of a completed workpiece is read from a drawing and the nozzle angles are then determined as shown in the above-mentioned flowchart. Since the nozzle angles correspond in a one-to-one relationship to the C-axis and the A-axis, adjustment to a perpendicular state and the angle designated in the drawing can be conducted easily and accurately on the known inclined portion of the workpiece, so that also the time period of the teaching work can be shortened.
As shown in the flowchart of FIG. 15, the teaching work in a three-dimensional laser beam machine having the conventional offset type head structure is easily conducted. However, the teaching work in an inclined portion of a workpiece or taper processing using a three-dimensional laser beam machine having the unidirectional head structure has a problem in that the accuracy of the nozzle angle at a teaching point in an inclined portion of a workpiece or taper processing is low because the W-axis and the U-axis are manually rotated until the perpendicular state is realized or the angle in the taper processing is attained, while the operator visually checks the nozzle angles in teaching, and also a further problem in that, as the number of teaching points is more increased, teaching requires a longer time period because teaching is conducted on each of teaching points.
In the teaching work in a three-dimensional laser beam machine having a head structure in which the processing point is not moved when the W-axis and the U-axis are rotated, the actual angles of the processing nozzle in the horizontal and vertical directions cannot be known from the angles of the W-axis and the U-axis as described in the prior art paragraph. For the user who previously had a three-dimensional laser beam machine on which an offset type head is mounted, therefore, such a teaching work is poor in easiness of the nozzle angle adjustment and low in working efficiency as compared with that in the case of an offset type head.
The invention has been conducted in order to solve the problems. It is an object of the invention to improve the efficiency of a teaching work in a three-dimensional laser beam machine having a head structure in which the processing point is not moved when the W-axis and the U-axis are rotated, by calculating and displaying the angles of a nozzle in the horizontal and vertical directions in an orthogonal coordinate system.
It is another object of the invention to provide a control apparatus for a three-dimensional laser beam machine which can easily establish a perpendicular state for a processing workpiece in which the inclination angle is known.
In order to attain the objects, according to a first aspect, in a three-dimensional laser beam machine having a head structure in which a processing point is not moved when a rotation axis and an attitude axis are rotated, the machine comprises: means for storing information of current angles of the rotation axis and the attitude axis, and calculating a nozzle direction vector from the angles; means for, based on the nozzle direction vector, determining angles of a nozzle in a vertical direction and a horizontal direction consisting of a Z-axis of an orthogonal coordinate system; and means for displaying the determined nozzle angles.
Furthermore, determination of the angles of the nozzle in the vertical direction and the horizontal direction is obtained on the basis of the nozzle direction vector from the angle of the nozzle in the vertical direction consisting of the Z-axis of the orthogonal coordinate system, and an angle in the horizontal direction consisting of an X-axis when the nozzle direction vector is projected onto an XY-plane.
The machine further comprises nozzle angle setting means for previously storing angles of the nozzle, and comprises notifying means for comparing with the determined angles of the nozzle in the vertical direction and the horizontal direction, to notify that the previously stored nozzle angles are attained.
Furthermore, the nozzle angles are displayed on a remote operation section such as a teaching box.
The machine further comprises nozzle angle setting means for previously storing angles of the nozzle, and compares with the determined angles of the nozzle in the vertical direction and the horizontal direction, whereby the rotation axis and the attitude axis of the nozzle are rotated and the nozzle is positioned to the previously stored nozzle angles.